The new business, which will provide customers with a variety of advanced testing capabilities and services, would have generated around $575 million as it stands in revenues last year.

But the companies said they also expect to benefit from opportunities to collaborate in other areas, including new ways to enhance patient recruiting and retention and accelerating the validation, development and commercialisation of companion diagnostics.

The transaction, which is subject to standard and customary closing conditions, is expected to close in the third quarter of 2015, after which Quintiles will own 60% and Quest 40% of the JV. Further terms were not revealed.